Do bigger tires affect your transmission?

Your transmission will shift according to the speed your going. Different tire sizes, big or small, will affect how the transmission shifts. For example, small tires will rotate two times as a big tire rotates one time, so the ratio is 2 to 1. If you have bigger tires you will travel further than smaller tires. Think of it as bigger tires are taking up more of the road, hence, you're covering more road per tire rotation.